Why Angry Birds is so successful and popular: a cognitive teardown of the user experience

The usual question: Over the past 40+ years as a consultant in the field generally known as human factors engineering (aka usability engineering), I have been asked by hundreds of clients why users don’t find their company’s software engaging. The answer to this persistent question is complex but never truly elusive. This question yields to experience and professional usability analysis.

The unusual question: Surprisingly, it is a rare client indeed who asks the opposing question: why is an interface so engaging that users cannot stop interacting with it? This is a difficult question because it requires cognitive reverse engineering to determine what interaction attributes a successful interface embodies that result in a psychologically engaging user experience. This question pops up when products become massively successful based on their user experience design – think iPhone, iPad, Google Instant Search, Nintendo Wii, Microsoft Kinect.

The interesting question: Recently clients have asked about the phenomenally successful casual computer game Angry Birds, designed for mobile phones, tablets and other platforms. For those who don’t have a clue what Angry Birds is all about, here is a quick synopsis. The game involves employing a sling shot to propel small cannonball-shaped birds with really bad attitudes at rather fragile glass and timber houses populated by basically catatonic green pigs. The basic thrust of the game is to bring about the demise of the pigs as quickly and expertly as possible by collapsing the pigs’ houses on top of their (sometimes) helmeted heads. Obviously, this sounds like a truly dumb concept. However, there is a catch.

Why is it that over 50 million individuals have downloaded this simple game? Many paid a few dollars or more for the advanced version. More compelling is the fact that not only do huge numbers download this game, they play it with such focus that the total number of hours consumed by Angry Birds players world-wide is roughly 200 million minutes a DAY, which translates into 1.2 billion hours a year. To compare, all person-hours spent creating and updating Wikipedia totals about 100 million hours over the entire life span of Wikipedia (Neiman Journalism Lab). I say these Angry Birds are clearly up to something worth looking into. Why is this seemly simple game so massively compelling? Creating truly engaging software experiences is far more complex than one might assume, even in the simplest of computer games. Here is some of the cognitive science behind why Angry Birds is a truly winning user experience.

Simple yet engaging interaction concept: This seems an obvious point, but few realize that a simple interaction model need not be, and rarely is, procedurally simple. Simplification means once users have a relatively brief period of experience with the software, their mental model of how the interface behaves is well formed and fully embedded. This is known technically as schema formation. In truly great user interfaces, this critical bit of skill acquisition takes place during a specific use cycle known as the First User Experience or FUE. When users are able to construct a robust schema quickly, they routinely rate the user interface as “simple”. However, simple does not equal engaging. It is possible to create a user interface solution that is initially perceived by users as simple. However, the challenge is to create a desire by users to continue interaction with a system over time, what we call user “engagement”.

What makes a user interface engaging is adding more detail to the user’s mental model at just the right time. Angry Birds’ simple interaction model is easy to learn because it allows the user to quickly develop a mental model of the game’s interaction methodology, core strategy and scoring processes. It is engaging, in fact addictive, due to the carefully scripted expansion of the user’s mental model of the strategy component and incremental increases in problem/solution methodology. These little birds are packed with clever behaviors that expand the user’s mental model at just the point when game-level complexity is increased. The process of creating simple, engaging interaction models turns out to be exceedingly complex. Most groups developing software today think expansion of the user’s mental model is for the birds. Not necessarily so.

Cleverly managed response time: A universal law of user interface design is “the faster the response time, the better”. True enough, there are applications where this is patently true. For example, Google has made this a mantra for their systems. However, surprisingly few software developers realize that response time management is actually a resource that can be leveraged to add to the quality and depth of engagement of a user interface. The surprising point that is often misunderstood is that not every aspect of the user interface needs to be or should be as fast as possible. Programmers uniformly have a really hard time with this one and few game designers take advantage of this potent variable. In most commercial software interfaces, response time management is completely overlooked even by those who claim to be UI design experts. The developers of Angry Birds managed response time in a way that goes far beyond simply “faster is better”.

For example, in Angry Birds, it was possible for the programmers to have made the flight of the birds fast – very fast, but they didn’t. Instead they programmed the flight of the angry flock to be leisure pace as they arc across the sky heading for the pigs’ glass houses. This slowed response time, combined with a carefully crafted trajectory trace (the flight path of the bird), solves one huge problem for all user interfaces – error correction. The vast majority of software user interfaces have no consideration for how users can be taught by experience with the system to improve their performance. This problem is a vast and complex issue for screen-based trading systems where error correction is not only essential, but also career threatening.

In Angry Birds game play the pigs also take a long time to expire once their houses are sent to bits. In many play sequences, seconds are consumed as the pigs teeter, slide and roll off planks or are crushed under slow falling debris. This response time of 3-5 seconds, in most user interfaces, brings users to the point of exasperation, but not with Angry Birds. Again, really smart response time management gives the user time to relax and think about how lame they are compared to their 4 year old who is already at the 26th level. It also gives the user time to structure an error correction strategy (more arc, more speed, better strategy) to improve performance on the next shot. The bottom line on how Angry Birds manages response time: fast is good, clever is better.

Short-term memory management: It is a well-known fact of cognitive science that human short-term memory (SM), when compared to other attributes of our memory systems, is exceedingly limited. This fact has been the focus of thousands of studies over the last 50 years. Scientists have poked and prodded this aspect of human cognition to determine exactly how SM operates and what impacts SM effectiveness. As we go about our daily lives, short-term memory makes it possible for you to engage with all manner of technology and the environment in general. SM is a temporary memory that allows us to remember a very limited number of discrete items, behaviors, or patterns for a short period of time. SM makes it possible for you to operate without constant referral to long-term memory, a much more complex and time-consuming process. This is critical because SM is fast and easily configured, which allows one to adapt instantly to situations that might otherwise be fatal if one were required to access long-term memory. In computer-speak, human short-term memory is also highly volatile. This means it can be erased instantly, or more importantly, it can be overwritten by other information coming into the human perceptual system. Where things get interesting is the point where poor user interface design impacts the demand placed on SM. For example, a user interface design solution that requires the user to view information on one screen, store it in short-term memory, and then reenter that same information in a data field on another screen seems like a trivial task. Research shows that it is difficult to do accurately, especially if some other form of stimulus flows between the memorization of the data from the first screen and before the user enters the data in the second. This disruptive data flow can be in almost any form, but as a general rule, anything that is engaging, such as conversation, noise, motion, or worst of all, a combination of all three, is likely to totally erase SM. When you encounter this type of data flow before you complete transfer of data using short-term memory, chances are very good that when you go back to retrieve important information from short-term memory, it is gone!

One would logically assume that any aspect of user interface design that taxes short-term memory is a really bad idea. As was the case with response time, a more refined view leads to surprising insights into how one can use the degradation of short-term memory to actually improve game play engagement. Angry Birds is a surprisingly smart manager of the player’s short-term memory.

By simple manipulation of the user interface, Angry Birds designers created significant short-term memory loss, which in turn increases game play complexity but in a way that is not perceived by the player as negative and adds to the addictive nature of the game itself. The subtle, yet powerful concept employed in Angry Birds is to bend short-term memory but not to actually break it. If you do break SM, make sure you give the user a very simple, fast way to accurately reload. There are many examples in the Angry Birds game model of this principle in action. Probably one of the most compelling is the simple screen flow manipulation at the beginning of each new play sequence. When the screen first loads, the user is shown a very quick view of the structure that is protecting the pigs. Just as quickly, the structure is moved off screen to the right in a simple sliding motion.

Coming into view on the left is a bevy of bouncing, chatting and flipping birds sitting behind the slingshot. These little characters are engaging in a way that for the most part erases the player’s memory of the structure design, which is critical to determining a strategy for demolishing the pig’s house. Predictably, the user scrolls the interface back to the right to get another look at the structure. The game allows the user to reload short-term memory easily and quickly. Watch almost anyone play Angry Birds and you see this behavior repeated time and again. One of the main benefits of playing Angry Birds on the iPad is the ability to pinch down the window size so you can keep the entire game space (birds & pigs in houses) in full view all the time. Keeping all aspects of the game’s interface in full view prevents short-term memory loss and improves the rate at which you acquire skills necessary to move up to a higher game level. Side note: If you want the ultimate Angry Birds experience use a POGO pen on the iPad with the display pinched down to view the entire game space. This gives you finer control, better targeting and rapidly changing game play. The net impact in cognitive terms is a vastly superior skill acquisition profile. However, you will also find that the game is less interesting to play over extended periods. Why does this happen?

Mystery: You probably do not know how to recognize it, but Angry Birds has it. To add context to this idea, mystery is all around us in the things we find truly compelling. The element or attribute of mystery is present in all great art, advertising, movies, products, and not surprisingly, interactive games. The idea of mystery in a user experience as an attribute for increasing user engagement is embedded in the idea of mystery (conceptual depth). We all experience the impact of mystery when we view a cubist period Picasso, recall the famous Apple 1984 super bowl ad, or listen to Miles Davis. He is said to have described jazz as playing the spaces between the notes, not the notes themselves. Mystery is present when you pick up an iPad for the first time. Why are the icons spaced out across the screen when they could be clustered much closer together to save space. Why does the default screen saver look like water on the inside of the screen?

Mystery is that second layer of attributes that are present but undefined explicitly, yet somehow created with just enough context to consume mental resources in subtle and compelling ways. At its most basic level, experiencing mystery in what we interact with makes you ask the question, “Why did they do that?”. What we mean here is, “Why did they do that? – A good thing, not “What were they thinking? – A bad thing. If you think carefully about the experiences you have in the ebb and flow of life, you realize that the most compelling are those that force you to think long and hard about why a given thing is the way it is. For example, why did Frank Gehry create the Guggenheim Museum Bilboa using the shapes he did? The famous architect could have created any shape concept, but why did he choose those shapes? It’s a mystery – we do not know and probably neither does he. What we do know is that his creation is cited as one of the most important works of contemporary architecture. In the same way that a building can captivate millions of sightseers, the element of mystery (conceptual depth) can help sell a few million copies of a simple interactive game.

Angry Birds is full of these little mysteries. For example, why are tiny bananas suddenly strewn about in some play sequences and not in others? Why do the houses containing pigs shake ever so slightly at the beginning of each game play sequence? Why is the game’s play space showing a cross section of underground rocks and dirt? Why do the birds somersault into the sling shot sometimes and not others? One can spend a lot of time on the Acela processing these little clues, consciously or subconsciously. When users of technology process information in this way, it is very likely that they are more deeply engaged than without these small questions.

How things sound: Over the past 15 years, the neuroscience of music has taken a huge leap forward. This new research is just beginning to tell us why music adds such a strong emotional component to movies, advertising, theater, and of course, new media of all types, including casual computer games. Employing the power of audio stimuli including structured music often adds a critical level of engagement for users of all forms of technology. Angry Birds’ audio effects and music seem simple but are, in fact, very complex. The use of audio effects and carefully varied melodic music lines works to enhance the game play engagement level. Many games do this but few do it expertly. The audio in Angry Birds serves to enhance the user’s experience by mapping tightly to the user’s simple mental model of conflict between the angry birds and the loathsome pigs. This concept, known in film production as “action syncing”, provides enhanced levels of the feedback for users at just the right time. For example, in Angry Birds, we hear the birds chatter angry encouragement to their colleagues as each prepares for launch. We hear avian dialogue as the birds arc toward their targets and hear the pained response from their victims when they strike their targets. The pigs are by no means silent. When the avian interlopers fail, they are often egged on to try just one more time by the snickering, grinning pigs. These consistently applied audio elements reinforce the player’s interactions and deepen engagement by emphasizing the anthropomorphic qualities of the main characters of the game and providing clever enhanced feedback during critical on-screen behaviors. What about the actual melodic music shifting from the foreground to the background without apparent reason? This musical thread running through the game play experience is mysteriously familiar and easily understood in the context of the overall theme of the game. Where have I heard that melody before? This combination of audio feedback is varied just enough that parents sitting in the next room are rarely prone to demanding an end to game play based on distracting musical repetition. Perhaps this explains the high number of hours spent playing the game!

How things look: Angry Birds has a look. One might characterize the visual style of Angry Birds as a combination of “high-camp cartoon” with a bit of greeting card graphics tossed in for good measure.

This leads to a more interesting question: How does visual design impact success in the marketplace? I routinely get this question from clients who are undertaking large redesign or new development projects. Decades after it first surfaced in automobile design, visual design is still the most contentious aspect of designing compelling user experiences. Designers (mostly of the UX stripe) routinely sell clients on the concept that the visual design (graphic style) of a given interface solution is a critical factor in success. This assumption seems to make good intuitive sense. However, the actual working principle is counter-intuitive. In most user experience design solutions, visual design (how things look) is technically a hygiene factor. You get serious negative points if it is missing, but minimal positive lift beyond first impression, if a user interface has great visual design. When we conduct user engagement studies for clients (not the same as usability testing), we routinely see data that strongly supports this theory. This concept does not apply to all user experience design problems, but in most cases it holds well. The ultimate question is how much visual design is enough? Even more important than good or bad visual design is appropriate visual design. On this metric, Angry Birds again has just the right set of attributes. The concept of appropriate visual design is in itself complex as designers generally apply too much rendering and engineers apply none, which often leaves the actual user staring at the equivalent of an engineering prototype (Google) or alternatively, World of Warcraft. After decades of experience in user interface design, I can predict fairly accurately the corporate software development bias of clients by simply examining the user interfaces of their products. I cannot imagine Google as anything but engineering-driven, despite the apparently large number of UX designers hired in recent years.

Measuring that which some say cannot be measured: How does one measure visual design in this context? There are several well-understood methodologies for assessing the appropriateness of visual design that we employ in development projects. These research methods make objective that which is thought to be only subjective. Visual design can be measured, rated, and scaled to the benefit of users and those who develop such interfaces. The actual dimensions of appropriate and winning visual design vary widely, depending on the application but in game design two factors reign supreme. First, the visual design must be memorable and second, it must convey the desired attributes of the game play model.

So memorable is Angry Birds that the developers have deals for real world “brand extensions”, including Angry Birds stuffed toys, t-shirts, and all matter of off-the-wall consumer goods that make BIG profits. The simple visual design of those tiny cartoon-ish birds is so compelling and simple, it brings an additional level of continuous interest to the game play experience. Of note too is the world the birds and pigs inhabit which changes in strange and subtle ways with every level. Visual design is another critical dimension of the success of Angry Birds, which leads to the ultimate question: Is Angry Birds the best it can be? Not by a long shot!

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MauroNewMedia has been helping major corporations and leading startups design highly usable and engaging products and software for more than 35 years. Visit our website for more information or hear a in-depth interview with Charles Mauro for more interesting insights.

We are left with the notion that a cognitive teardown of a truly compelling user experience is vastly more interesting and insightful than simply answering the opposite question: why is a given user interface dysfunctional? To summarize, in the context of Angry Birds, success is bound up in slowing down that which could be fast, erasing that which is easily renewable, and making visual that which is mysterious and memorable. Over the past 10 years, our firm has conducted user engagement studies on hundreds of user interfaces. The vast number did not get one principle right, much less six. You go Birds! Your success certainly makes others Angry and envious.

Hi Charles,
This is indeed a great reverse analysis of a great product. As Howie asked if the original programmers were aware of what they were doing when they built this. I mean is this thought out design or just gut driven design that is just brilliant!

One thing I would like to add is the superior level reset in Angry Birds. So many games fail to pay attention to the mechanics by which the user would restart the level (i.e. putting random buttons on secondary screens, unnecessary splash objects, etc.). I do not believe that it is an accident that you can quickly cut your losses and start from scratch before your brain is able to calculate the reward/punishment statistics in terms of continuing the game vs. doing something more productive.

Even in restarting the level you’re still performing a motion that does not disturb the flow. On tricky levels where birds must be all accounted for to hit the 3-star score you cannot fumble your opening shot. The pause/restart action becomes just as essential and sees heavy use.

The level reset is wonderfully integrated into the game where you perform an L-shape move. It does not take your out of the game or put random screens with tons of options on it (like many others do).

Sundeep: Good question. My opinion is that they hit on some of these attributes by chance and some through exercise of the game design in prototype development. With a suitable amount of user testing (even by the developers themselves) it is possible to create fairly high levels of game-play engagement. However, applying some cognitive science takes it to an even higher level.

Hello, I am Brenda Burkhart, a fellow CPE who has spent my entire career analyzing, specifying and designing software for users. You mention performing user engagement studies for clients (not the same as usability testing). Could tell me a little more about what you mean by this and how/what aspects of user engagement that you study?

I think that ALL iphone games are so addictive! at first when i saw my friends playing i thought it wasn’t but after getting my iphone and downloading games i became addicted! the point is.. you just have to start playing any game and you’ll and up like that.. maybe angrybirds got the attention and many people started to play(its fun :P)

I think angry bird’s success comes from more than just good ux design, as someone said earlier. It’s got great marketability, range of audience, storyline… It came at the perfect time with the rise and hype of iPhones, iPads and all things touch. It’s the fortunate convergence of a lot of factors, which includes good design, but imo not that groundbreaking.

Even Vesterbacka himself admits that the success of Angry Birds depended heavily on the success of mobile apps on the iPhone:

@popculpo
Where did you get that from?
Screen saver activates when you are idle for a certain amount of time (if you haven’t turned that feature off).
Desktop wallpaper is a background of your (“active”) screen.
But I guess you already knew that.
So I just wonder, how did you come up to that “mystery”? 🙂

Doug25 & others who think it’s all based on media-hype: I really have to disagree. When I first started playing this game, there was no media blitz, it had been sitting at #1 in the iTunes App Store for many weeks and my curiosity finally got the best of me.

AB is a game for non-gamers. Gameplay is simple, the rewards are many and often, hence, continued play from all players. Any game that increases in difficulty and/or timing & speed too quickly I’ll drop out of. (good example: Cut the Rope, great game, but in the higher levels you have to use 2 hands to solve puzzles, and be fast, and go through lots & lots of careful steps to solve)~ AB is always the same: slingshot, birds, structures w/pigs.

I think the fact that players are frequently rewarded (it’s easy to pass a level, not so easy to 3 star a level) plays a huge part in why AB is so popular, especially with people who are not hardcore gamers.

I think the answer to the response-time question is much more straightforward, and much less. In fact, this isn’t even a response-time issue, because the response is immediate (the bird begins flying as soon as you let go of the slingshot).

The proper basis for comparison is to a video player. When playing a video, you want the video to start playing as soon as you hit the play button (immediate response). What we are looking at here, then, is not a response-time question but one of feedback-bandwidth. Is the video running at a speed where the viewer can take in as much as the maker of the video wants him/her to? We’re all familiar with poorly-shot home videos and suchlike, where sometimes the video sweeps across a scene so quickly that the viewer can’t take it in, and sometimes it lingers on unimportant details for far too long.

Applying this to Angry Birds, then, it’s not difficult to notice that the physics of the game are running at a speed slightly different from real life. In fact, they’re running at a speed that is just slow enough for the player to take in the feedback at a surface level, but not so slow that the player has time to get bored. This is especially notable given that different players will naturally have different levels of ability w.r.t. dealing with the feedback stream.

Personally, I have a problem with Angry Bird’s physics. I can kind of see why that game would catch on, but I don’t think it’s nearly as addicting as the 80’s most addicting game, Tetris. Man was I hooked on that game.

To all who commented this week: thank you for the many positive and interesting responses. The post has created a surprisingly large number of views and has spurred large message threads on other blogs. We sincerely appreciate your readership and thoughtful responses.

Hi Charles, while I enjoyed your article, your posthoc speculations really have nothing to do with cognitive science. You describe engineering features which make the game pleasant to use, but nothing you have said explains why the game promotes addictive behavior. Reinforcement theory, reward learning and other cognitive principles would provide a better answer to your question.

Great post, interesting comments. As a teacher of game design this is a fascinating explanation of so many intricate moving parts of a successful game. I appreciate the term “tear down” and may replace my current “break it down”.

Angry Birds is so successful, because it ripped off a thirty year old game concept (tanks, scorched earth, etc) and charged $20 for it from casual gaming idiots who have never played a game in their life that wasn’t on Facebook, until now.

Richard: Thanks for your comment related to cognitive science and its relationship to our post. We appreciate all positive points of view.

However, to be clear, the post is not written for or directed at the deeper theoretical constructs you mention. That being said,I must disagree with your premise that the issues raised do not track to cognitive science. For example the points discussed in our post that relate to both response time and memory management can appropriately be aligned with the “schedules of reinforcement” concept clearly articulated in Reinforcement Theory. I think you may be reading the definition of cognitive science too narrowly.

On the other hand, as you state well in your comment it is certainly possible to map the game’s impact on cognition and engagement to any number of cognitive science theories and as such a discussion would be interesting and relevant. However, it was our goal to draw a connection between simple machine behaviors and the impact such attributes have on user engagement.

As you probably know there is a far more robust game-research literature which posits connections between game design and engagement. In fact much of that literature covers the same conceptual framework as our more simple piece but does so with more intellectual rigor. Nothing wrong with that approach, just not what we felt was appropriate for those who read our blog.

Finally, I think it would be relevant and interesting for someone (possibly you) to frame that more academic literature and related insights against Angry Birds.

I found the unofficial PC port of the game and tried that. While it might not be exactly the same experience, all the things you mentioned should be there. And I hated the game – how unresponsive it was and how it tried to make my efforts useless with every move I made. The conclusion: another overhyped game.

Worms and tanks and other games like this at least had physics. I don’t know if there were any in this game, it seemed to be random. And it’s in pseudointellectual’s nature to perceive random/dumb things as something clever.

I’m compelled to agree with desreveR, not least because Angry Birds has rather a lot in common (to put it kindly) with the earlier Crush the Castle – a game which has not enjoyed quite the same degree of success.

There are differences: Rovio polished it up nice with their art-style as you mentioned, and their choice to use a pleasingly tactile slingshot mechanism as opposed to Crush the Castle’s more challenging and therefore considerably less accessible trebuchet was a very wise one, but I suspect there came a point in Angry Birds’s sales where these considerations were rendered essentially trivial by sheer force of brand-recognition.

To me, this piece is an attempt to explain why Angry Birds continues to be played and continues to occupy mindshare.

“Media hype”, whatever that may be, and marketing will only get you so far. I have played similar games and discarded them because they are not compelling.

If a later-to-market product enjoys more success than a precursor, it’s not always just down to marketing. Refinement, polish, improved design, whatever you might call it, these are important factors even if they seem intangible to many people. Often more so than the manufacturer or developers’ more usual response to competition of feature creep which often results in a degraded user experience.

I’d argue that you forgot to include one other important point: the ease for a user to end the current round and start again when a mistake is made. This makes the game particularly compelling for me: it’s so easy to try again.

Great article with some very interesting points, but one large factor was missed: intermittent rewards. A shot is only occasionally successful, or at least requires much practice to improve. For instance, compare the entertainment value of driving nails into a board vs. playing whack-a-mole. Driving nails is boring by the time you finish the first nail. Whack-a-mole is entertaining until you reach the point where you never miss (or possibly at the point where you cease to improve). Slot machines are entirely based upon intermittent rewards.

Certain blocks shake at the start of the level, due to instabilities in the physics engine (Box2d). The level designer didn’t place the blocks in the exact precise position, and they shift slightly (perhaps less than a visible pixel), causing pushes against other blocks, and these tiny oscillations can cause the simulation to react in non-deterministic ways. Once I saw a stack of blocks start vibrating and fall over, before I even launched my first bord.

I believe that a little bit of randomness is intentionally introduced in the block placement at the start of a level, which increases the number of possible outcomes for a given initial ‘shot’. If the blocks fell over the same way every time, the game would become more predicable which leads the player to get bored more quickly.

To those who think this game is only popular because of the hype surrounding it: I disagree. Just because YOU don’t like the game it doesn’t mean that someone who does like it must be brain-washed by the hype. This is a case where the hype comes from the popularity, not the other way around; and the popularity comes from the fact that the game is compelling for a lot of people.

To those who accuse Angry Birds of ripping off other games: so what? There are very few truly original game concepts anymore. Most new games borrow/steal from other games, which themselves borrowed/stole from yet older games. A game can distinguish itself with good UI, sound design, and art design even if its gameplay mechanics are completely unoriginal — i.e., the execution is as important as the concept.

AB is an example where quite a lot was done right with its execution, which I think leads directly into its success.

As steve said, the slight shaking is from the physics engine Box2d. This is a consequence of using Box2d, was not intentional on developers part. I’m going to talk more about Box2d. Box2d is an open source 2d physics engine (http://www.box2d.org) that has been around for ages and is used in many many many games. This article gives way too much credit to the developers for programming the game in such a way (leisurely glide, suspenseful teetering and wobbling, etc). That is all default behavior of the Box2d physics engine. When two rigid bodies in the engine collide, they will continue to react realistically until they come to rest. This sometimes takes a very long time, and anything using Box2d will do this. There is actually very little work programming it, all the heavy lifting is done for you out of the box. I’ve put together similar prototypes of this gameplay in the past in less than a day. The gameplay of this game certainly isn’t original. This type of “slingshot projectile into objects” game has been done a million times and is very popular within the Box2d community. What Angry Birds did is skin the game really well and get lucky. I’m sorry if I came across as bitter, I just wanted to clear some things up and give credit to the creators and contributors of the great Box2d.

Brilliant post! thanks for the autopsy. Talking about a game like this is best with a coffee/beer in hand.
I can’t help but wonder what is the roll of word of mouth in the success of this particular case.

You totally lost me with “Coming into view on the left is a bevy of bouncing, chatting and flipping birds sitting behind the slingshot. These little characters are engaging in a way that for the most part erases the player’s memory of the structure design, which is critical to determining a strategy for demolishing the pig’s house.”

There is nothing engaging about the birds. You don’t care about an individual bird for any length other than the flight from the slingshot to the pig house. Suggesting that they are is an insult to John Marston. Marston, from 2010’s Red Dead Redemption is actually an engaging character, with a storyline and *SPOILER ALERT* tragic end that you actually care about.

You don’t come away from Angry Birds thinking about how heroic it was for Larry the Bird to crash into the pig’s house in 1-4.

The response time points are noteworthy, as it does seem that it gives the user more of a vested interest in the game. If the game were just flinging things at objects, I guess people would not feel as connected to the characters. This, I suppose is evidenced in the fact that a movie is being made after the game. I wonder how much of this was preconceived vs. a good developer’s innate understanding of what seems to work well.

Wow what a deep analysis. Most of this was extremely insightful. However I do think the best thing you can do for usability is think of how you would personally (and objectively!) want the game to work and go from there. That is much easier than trying to come up with deep formulas. Really great stuff though, thanks for sharing!

Nice and comprehensive write up. But I still don’t get why it’s so popular. It frustrates the heck out of me! You can get stuck on a level simply because you can’t get all you “flings” right. And if it’s the last one you screw, you gotta start all over again.

To me, as a game, it sucks, because there’s no reward for progress within a level. As a minimum, it should have an undo option. Sometimes you really need it coz you accidentally misfire.

I wouldn’t care if it cost me points for undoing. When I have played Angry Birds it wasn’t to get the most points, it was simply to complete the levels. However, once I get stuck on a level, and just can’t get all my “flings” right, after considering heaving my iPad across the room, I give up in frustration, and rant about how crap Angry Birds is.

I know I’m obviously in the minority but having an undo wouldn’t spoil the game for those who’d like to do it without, and it would add to the enjoyment for those would use it.

I’ve been considering this question myself. Clearly, a game that is basically a catapault clone must have something extra to it, but I never considered that there would be THIS much depth to Angry Birds!

Very insightful…loved it.
Don’t know if the points you mentioned were incorporated deliberately in the game or not; but a thing I have observed so far is that good designs automatically take care of the simpler nuances/components of good design, consciously or subconsciously(most of them). E.g. A ‘good’ chair will already have ergonomics taken into account while designing.
And I definitely don’t think the HALO EFFECT came into play here (“Is Angry Birds the best it can be? Not by a long shot!”).
I’d like to think of this article more as a case study.
And THANKS again!! 😀

Hi, I am in the process of writing a blog post entitled What Angry Birds and Righteous Pigs can Teach us about Meeting Design. And would like to include a quote of yours from your blog post in Jan. 2011 as follows:

Great article!
Another key element is the fact that the camera zooms out to show both a bird and the castle. Instead of other games where the camera looks at the canon ball or at the castle, the camera here tracks both. Being able to show the space between the bird and the castle when you overshoot is essential to the learning experience. Without access to that key information, it is impossible to do better and learn when you have played your worse.

Wow, this is a great article, looking at the game from a different point of view. I know the media and hype and word of mouth have done a lot to make this game popular, so has social marketing like twitter, etc. I learned of this game by word of mouth, from my kid of course, and I find it to be a nice relaxing, fun game to distract me from life for a while, but I’ve never found it addicting.

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I think the combination of many small but significant factors together makes this game so successful and popular because there have been many games like this before, but none even close to its popularity.

This is a really interesting article. It’s weird how this simple game has taken such a foothold in pop culture.

Maybe I’m oversimplifying, but to me the draw of this game is not unlike other simple activities such as rocking or twiddling. Maybe it’s the simple, repetitive action that is soothing and relaxing and what makes it become addictive.

one can overplay marketing i feel, after all, what is marketing if people dislike the product?

whether by design or happy good fortune, many artfully crafted aspects come together in this game, to make it a real joy. my personal favourite is the Jewish styling’s of the background music, there’s such comedy in it. ay ay yay! what is it with these green pigs?!

Hi there, nice article. I think angry birds is a true example of how anyone with a good imagination can turn that into a sucess. First everyone was lemmings mad now it’s angry birds. Both simple but highly addictive concepts – from a fellow addict!

Does engagement go beyond the usability mechanics? Cuteness of concept, range of audience, and story – obviously. Could Angry Bird’s success be taken to a whole new level of addiction and attention through more psychologically relevant rewards, social game mechanics, and meaningful revelations of the mystery?

Excellent article, but I missed any mention of the Golden Eggs. Accumulating them adds elements of the unknown (not knowing when they’ll appear) and challenge (since to acquire them, you have to achieve three stars per level, instead of just moving on with one star), as well as entertainment, since the little Golden Egg games aren’t as mentally taxing as the regular levels. Surely that plays a role.

while the analysis is on point, i think the lessons to learn from it are much less arcane and it would behoove UI designers to periodically take a step back from that level and focus on how the overall dynamic engages the intuitive faculties of the user. what i think appeals to many in angry birds is its direct correlation to a fundamental area of physics that we all constantly deal with on an extremely intuitive level, that being ballistics. pair that straightforward, real-world concept with the more complex yet similarly intuitive house-of-cards targets that hold promise of thrilling chain reaction victories and you have a simple yet impossible to master scenario, very much like golf. to me the mystery and SM management simply represent ways of including randomness and further calling on the intuitive faculties of the game player

Actually, it’s not a mystery why Gehry designed the Guggenheim the way he did. He wanted to create an easy walking experience for visitors so that they could focus on contemplating the art, rather than schlepping through the museum space. Visitors are meant to take the elevator to the top of the building and stroll down — the continuous spiral path and gravity reducing their effort.

I still prefer crush the castle, and I am suprised so few people referenced it. Angry birds is too cartoony for my tastes, and I can’t play it for more than 20 minutes before succumbing to boredom and thus uninstalling it.

The author is remiss in pointing out the obvious: some big chunk of Angry Bird’s addictiveness is because the base activity is a fun thing: it is fun and pleasant to launch a slingshot at a building of blocks.

i own it both on my iPod and my droid incredible……yes its addicting…….i cant put it down for more than an hour or two……it is the definition of addicting……sure maybe the majority of hc gamers wont get addicted but its like super Mario…..anybody can play but only the addicts will completely beat it….just because its simple doesn’t mean its not addicting

I agree with your post. My explanation of why Angry Bird is so popular is partly due to all the hype that is placed on the game itself. I totally agree that the game is very easy and simple to play. It doesn’t need any instructions on how to play. Anyone can pick up their devices and starts playing this game without having to be taught how to play. Plus, the game itself has a great story that goes along with the game. Birds are angry at the pigs, because they took their eggs and eat them. So, they are angry. Thus, they are called angry birds, who wants to take revenge. This game has no age limit. I think that is one of the biggest reason why it is so popular.

Wonderful piece. I would only add one extra layer, which relates directly to everything written here. What happens in Angry Birds runs counter to all of our expectations of the physical world and of video games, which either seek to replicate the real world or produce a hyper-ized version of its reality. In Angry Birds, by contrast, the result of every movement is contrary to our innate expectations. A powerful slingshot hurls something slowly. The slowly moving object has a strangely enormous impact on its target; and yet the result of the impact happens slowly and methodically, not with random fury, as we’d expect.

This confounding of our innate expectations for the visual, physical world, can be instinctively hilarious. A few cases in point: 1. I’ve seen tiny babies laugh uproariously when they first see a ball bouncing up to them. Imagine how delightfully absurd that must look. Nothing else in their world has ever done that? 2. As a youngster, I watched a friend bend a school cafeteria fork into an L shape. I thought it was hilarious: my laughter was instant and instinctual.

The common thread here is a fascinating confounding of our expectations for the natural world. I think it has a powerful, absorbing, freeing, intoxicating effect on us. To me, Angry Birds is funny, for precisely the reasons I state; in that regard, it’s hugely ironic. It’s saying, silently, “Look at the way we’re toying with reality.” this cognitive subtlety is a kind of irony, relative to the utterly juvenile visual entertainment wrapped around it.

There are definitely a variety of details like that to take into consideration. That may be a nice level to carry up. I offer the ideas above as common inspiration but clearly there are questions just like the one you bring up the place the most important factor will likely be working in sincere good faith. I don?t know if best practices have emerged round issues like that, however I am certain that your job is clearly identified as a good game. Each girls and boys feel the influence of only a moment’s pleasure, for the rest of their lives.

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I dislike Angry Birds as of now. I don’t like seeing it every single place I go to. 🙁 But I have to hand it to them, the game is way fun and entertaining! It just promotes animal cruelty though. 😐 Eeeeep! All in all, I recommend it even to the oldies!

The author really should have learned to use good timing in his article. This is overrun with words and redundant and you eventually realize you don’t care enough about why Angry Birds is so addictive to continue reading it.

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I think a lot of people have commented that this is a great hindsight view, but can you pay attention to these points when you are designing. Or at that time it just comes from the gut.

IMHO, (good) designers can include some of these in their daily practices. One thing that I might to is print out certain words like “short term memory”, “engagement”, “response time” and pin them on my board. When I am designing something, I would stare at them and mentally walk through how my design is working on these parameters.

Also, all (good) web products go through a journey of evolution. One should start evaluating one’s design on these ‘non obvious’ parameters once the page is settled.

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I agree with Howie. while this game may prove a paragon of UX virtue, I have to suspect that many of these factors were the results of finely honed instinct around gameplay more than conscious decisions about “adding a mystery factor” or “challenging the user’s short-term memory load”.

Just as one example, “Why is the game’s play space showing a cross section of underground rocks and dirt?” is a great question, but to me that can be answered in a few simple and practical ways.

First, it adds texture and visual interest to the overall game play… if the houses and birds were on the ground, the user could see more of their arc… but it would be a very empty-feeling environment.

Additionally, the use of that space helps to make the entire game experience comply with the “rule of thirds” of visual composition, used to help guide the user’s eye. With the addition of the underground bits, the birds and the pigs appear at the top of the lower third of the screen, often where horizon lines are placed in photographs and paintings, a natural draw for the eye.

Oh, and let’s not forget the fact that an integral part of the controls involves dragging down and back from the slingshot, and having it sit right on the ground at the bottom of the screen would not leave ample space to interact with it properly.

I would expect that all of those thoughts might have occurred to the programmers before they thought “let’s add in a mystery factor!” I agree that the mystery factor does add value to any interaction, but I suspect that when things like that grow organically out of the creators’ own experiences, they come off better than when a team goes down a list, checking off attributes.

I agree with Howie. while this game may prove a paragon of UX virtue, I have to suspect that many of these factors were the results of finely honed instinct around gameplay more than conscious decisions about “adding a mystery factor” or “challenging the user’s short-term memory load”.

Just as one example, “Why is the game’s play space showing a cross section of underground rocks and dirt?” is a great question, but to me that can be answered in a few simple and practical ways.

First, it adds texture and visual interest to the overall game play… if the houses and birds were on the ground, the user could see more of their arc… but it would be a very empty-feeling environment.

Additionally, the use of that space helps to make the entire game experience comply with the “rule of thirds” of visual composition, used to help guide the user’s eye. With the addition of the underground bits, the birds and the pigs appear at the top of the lower third of the screen, often where horizon lines are placed in photographs and paintings, a natural draw for the eye.

Oh, and let’s not forget the fact that an integral part of the controls involves dragging down and back from the slingshot, and having it sit right on the ground at the bottom of the screen would not leave ample space to interact with it properly.

I would expect that all of those thoughts might have occurred to the programmers before they thought “let’s add in a mystery factor!” I agree that the mystery factor does add value to any interaction, but I suspect that when things like that grow organically out of the creators’ own experiences, they come off better than when a team goes down a list, checking off attributes.

On the whole, however, this article is a FANTASTIC overview of some of the many features that go into creating a great and engaging user experience. Thank you!

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A great blog .. but no mention of a users privacy experience on Angry Birds? The user has no ability to control Rovios collection and use of a range of data – such as location or UDIDs. This should be fundamental to all app design.

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One question for you or anyone on Angry Birds’ UX interface, and why you don’t think anyone has noticed or fixed this:

Most people are right handed and want to launch the birds with their right hands, so when you do use your index finger of your right hand on say the iPad version of Angry Birds, as you pull back the slingshot, your hand obscures the play area which is annoying and makes me tilt the iPad at an angle in order to not have my palm obscure the pigs as much when I launch birds.

Why not just have the game right to left, so you’d have more viewable game area? After reading your article, I’m assuming this isn’t a mistake and that subtlety make the game harder?

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Brilliant article, exactly what I was hoping to find and more. And great comments too.

There’s another article that talks about another dimension of Angry Bird’s popularity – its promotion, community, etc.http://www.elearningmag.info/?p=73
It is the second of two great articles.

I also appreciated that the initially wobbling structures implied fragility, giving you the expectation of success. There is something innate about enjoying destroying stuff, as any parent of a 2-yr old boy can attest, (I’d love to know the gender of players). Your repertoire of knowledge is both tactile and strategic. Often you succeed for unintended reasons, providing random blasts of perceived luck. The slow collapse of structures is edge of your seat suspenseful and exciting, as you urge particular structures to fall in particular ways. Occasionally a level is easier than the trend, giving a bit of a breather. The UI is perfect for imprecise touchscreens, in that precision is only ever needed slowly. Free daily awards keep you coming back and ensure you keep in-game purchases enabled (as disabling them disables the freebies). I found one egg, and assume this encourages people to dig deeper. It uses the classic good versus evil narrative, although it is so simple and auxiliary I’m not sure it makes a lot of difference. And success involves a SEQUENCE of correct catapults, so if you get a few partly right, (or even just promisingly close), and then you make a mistake, you have reason to expect you are capable of doing better on your next attempt. The slight randomness of the physics engine encourages you to hope for luck.